A preferred method for the removal of a body part is ligation. Ligation is a process in which a band or chord is fastened to a body part to be removed in order to constrict it, thus cutting off the supply of blood and systematic support. The body part thereafter atrophies and drops away from the body. Ligation is used for many purposes including castration and removal of horns, tails or other body parts from animals.
Ligation has a number of advantages over surgical procedures for such applications. First, ligation has a safety advantage in that the animal normally does not become susceptible to infection. For example, in the case of castration of bulls, a period of about two weeks to a month typically passes between the time that the ligature is attached to the scrotum and the time that the scrotum drops off. During this time the area adjacent to the ligature heals, thus reducing the likelihood of infection. Another advantage of ligation is that ligation can be performed critically by non-expert personnel, thereby reducing costs. In addition, when the ligature is sufficiently tight, ligation can generally be performed with little stress on the animal because the body part numbs quickly after the blood supply is cut off.
Known ligation devices for use with the younger male animals include elastrator rings. Elastrator rings may be applied to an animal with the use of a scissor like instrument capable of expanding a rubber ring which may then be placed in a desired position, the handles released, and the tool withdrawn. Elastrator rings may suffer from drawbacks of supplying insufficient or excessive tension to a body part. Insufficient tension may result in unsuccessful ligation in addition to infliction of pain upon the animal, thus frustrating the purpose of ligation. Known elastrator rings, while broadly used around the world due to their inexpensive cost, are considered one of the most stressful procedures an animal can experience.
Another ligation method is disclosed in U.S. Pat. No. 4,691,704 to Wadsworth, which is hereby incorporated by reference in its entirety. A loop of a ligature elastomeric band is formed around the body part to be ligated, and then an end portion of the band is attached to a lever arm. The lever arm can then be retracted in a substantially linear fashion by successive pulls on a trigger mechanism, thereby tightening the loop. However, the process of tightening the loop through successive pulls on the trigger mechanism is time consuming and the animal must therefore be restrained for a relatively long period of time. In addition, the tension which can be imparted to the band, and the tightness of the loop, are limited by the hand strength of the user, the length of the rod, etc. Moreover, relatively large frictional and abrasive forces are exerted on the band where the band is attached to the lever arm, thereby increasing the likelihood of damage to the elastomeric material, causing breakage before the desired tension is achieved. Additionally, due to the design of the ligature tool, an operator is limited in the extent to which the band can be tightened. Once an operator has fully retracted the lever arm, the loop's tightness cannot be increased.
Another method of ligation is disclosed in U.S. Pat. No. 5,236,434 to Callicrate. Callicrate discloses a method and apparatus for ligation including the steps of forming a loop about the body part with a band of ligature material and winding the band to tighten the loop. The band may be tightened by securing the band to a spool and then rotating the spool to align the band. After the loop is tightened the loop can be secured by crimping a grommet so that the band is secured therein.
It is known in the art that proper and successful ligation often requires a sufficiently precise amount of tension to be applied to a band. The application of excessive tension may cause the band or device being applied to break. Conversely, when inadequate tension is applied, ligation efforts may prove unsuccessful, subject an animal to pain, and often result in a user resorting to conventional and less desirable methods of surgical castration.
Prior art devices that employ an endless loop or band are known to provide flexibility in that they may accommodate a variety of different sized body parts and different amounts of tension. However, it is known that such devices require cutting or severing of at least a portion of the band after tension is applied. This cutting may result in various complications, including breakage of the band, and gaps being formed between a band and a band clamp. Moreover, provision of a sharp cutting tool, whether or not associated with a ligation tool, is inherently dangerous and can result in undesired harm to an operator. Prior art devices which require separate cutting tools for performing ligation procedures may frustrate ligation procedures or place a user in harm's way when such a tool is misplaced or forgotten.